1. Field of the Invention
The present invention relates to epoxy resin compositions which are fast-curing and effectively moldable and cure into reliable products without a need for postcure. The invention also relates to semiconductor devices encapsulated with the compositions in a cured state.
2. Prior Art
The semiconductor devices in use today are predominantly resin encapsulated diodes, transistors, integrated circuit (IC) chips, large scale integration (LSI) chips, and very large scale integration (VLSI) chips. Resin encapsulation is usually carried out with epoxy resin compositions because epoxy resins offer superior properties (e.g., moldability, adhesion, electrical characteristics, mechanical characteristics, and moisture resistance), compared with other thermosetting resins.
For cost reduction and energy saving purposes, there is an increasing demand for epoxy resin compositions having adequate molding properties including fast-curing and curing into reliable products which can be used without postcure.
However, if the amount of catalyst is increased for endowing fast-curing properties, the resulting epoxy resin compositions have many disadvantages including a shortened gel time and an increased melt viscosity, which cause under-filling, voids and gold wire shifts. In addition, these compositions have poor shelf stability and provide less reliable encapsulation of semiconductor devices.